Pennsylvania is perhaps the most crucial swing state to win in this election, just as it was in 2020. But there have been big changes in the state since last time in terms of registered voters .
One reason Republicans are optimistic about their chances of taking back the state is the number of registered voters in Pennsylvania: Although there are still more registered Democrats than registered Republicans, as of March 2021, there were 630,000 more registered Democrats than Republicans in Pennsylvania. By October 2024, this gap has been halved, now standing at around 300,000.
Several factors cause changes in voter registration numbers. First, some existing registrations are removed from the rolls when those people die, move, or go too long without voting. Existing registrants also sometimes change their registration party. Finally, new registrants are constantly added to the lists.
To better understand which of these factors is causing Democrats’ narrowing registration advantage in Pennsylvania, the NBC News Decision Desk merged individual registrations from its voter database in March 2021 and October 2024 to track how registered voters moved between parties and statuses.
The chart below illustrates all changes in registrants’ parties over this period. Overall, this shows that there are about 110,000 fewer registered Democrats in 2024 than in 2021, and about 220,000 more registered Republicans.

Previously registered voters who switched parties were the largest factor in narrowing Democrats’ registration advantage. More than 160,000 people who were registered as Democrats in 2021 are now registered as Republicans. Conversely, only 58,000 Republicans switched to Democratic registration during the same period.
Additionally, another 83,000 people registered as Democrats in 2021 are no longer affiliated with a major party. Just over half of previously registered Republicans — 50,000 — did the same.
Second, registration suppressions also helped reduce Democrats’ registration advantage. There were about 430,000 Democrats in 2021 who are no longer registered in 2024, compared to about 330,000 Republicans.
But new voter registrations have not played a role in narrowing the Democratic Party’s registration advantage. In fact, slightly more people registered since 2021 are now registered Democrats than registered Republicans.
The Electoral Impact of Registration Changes
How might these changes affect 2024 election? Looking specifically at voters who cast ballots in the 2020 election could help answer this question.
If we simply consider 2020 voters who have switched parties since then, about 130,000 registrants who were Democrats when they voted in 2020 are now registered Republicans.
Conversely, only 47,000 registrants who were Republicans when they voted in 2020 became registered Democrats.
In 2020, more independent voters registered as Republicans than Democrats. Finally, among the 2020 voters whose registrations have since been deleted, Democratic registrants slightly outnumbered Republican registrants.

Another big part of closing the party registration gap comes from removing the registrations of people who didn’t vote in 2020. About 240,000 Democrats’ non-voting registration records have been deleted, compared to around 160,000 non-voting registration files for Republicans. Party switching also plays a smaller role: 31,000 former Democrats became Republicans, compared to 11,000 former Republicans turned Democrats among the 2020 nonvoters who have switched since then.

An important caveat to consider: People vote for candidates, not parties, and they don’t always vote for candidates who match their partisan identification. Additionally, registrants may experience changes in their partisan identification over time, and a change in their registration will not necessarily occur at the same point in the process as a change in their voting preference. One way to assess the strength of partisan identification is to examine how stable party registration is for registered voters in Pennsylvania who have moved counties. This is a key group to focus on as these individuals need to re-register in their new county – and therefore reaffirm their party of registration, giving an updated indication of how they view their current party identification.
The graph below shows that an overwhelming majority of registrants choose the same registration party in their new county as they did in their old county. But a small number are changing. And consistent with our analysis above, slightly more people choose a Republican affiliation and slightly fewer choose a Democratic affiliation when re-registering.

So what are the potential electoral consequences of these changes in party registration? As for voter registration suppressions, the impact is unlikely to be significant, as most Democratic-leaning groups that disappeared from voter rolls did not participate in the 2020 elections.
It is less clear what to think about party switching, because only some of the factors driving party switching would have electoral consequences. Some registrants may have supported a different party long before officially changing their registration to match their voting behavior. Others, motivated by Pennsylvania’s closed primary system, may have switched parties so they could vote in one party’s primary.
The most consequential shift would be registrants switching affiliations in response to recent political conditions, making these changes a sign that people may shift from supporting one party in 2020 to another party in 2024. Unfortunately, there is no easy way to know how much of these party shifts occur for these different reasons.
One thing is clear: Given that the state is evenly divided between Democrats and Republicans, the candidate choices of Pennsylvania voters who do not hold party identification are likely to play a significant role in determining the nominee who will prevail in the state – and perhaps overall. 2024 presidential election.